The present invention concerns an etching method and apparatus that allows etching of very small features with great uniformity and, in particular, using polyimide as a mask in vapor hydrogen fluoride (“HF”) etching.
As microstructures decrease in size, it becomes more difficult to selectively etch individual features of many devices. Conventional wet etching processes, although capable of selective etching, often cannot handle very small or finely detailed etching tasks because the wet etching process is limited by surface tension of the etching solution and air bubbles contained within the etching solution. In contrast, conventional plasma etching techniques enable more detailed etching but cannot be selectively controlled with a comparable degree of precision. In short, current etching techniques fail to provide a suitable method for selectively etching very small features and, in particular, for selectively etching very small features in a uniform-manner.
Accordingly, an improved method and apparatus for accurately and uniformly etching very small features is desired.